2003 150 Yamaha 4 stroke pulses at idle

[nediver]

I'm purchasing a used parker 21 with a 2003 150 Yahama 4stroke. At idle in neutral the motor seems to pulse....much like opening the back window of your car causes a pulsing. The dealer says they all do this at different rpm's. I'm taking it for a sea trial next week and wanted to know ahead of time as much about this pulsing as I can. Does anyone have any idea what's causing it?

Thanks,

nediver

 

[Capt Ken]

They do not naturally do this. Sounds like an Idle Air Control valve malfunctioning. Have the dealer show you a printout of YEMS check.

 

[nediver]

OK...........sorry, but what is a YEMS?

 

[Capt Ken]

It's the Yamaha diagnostic system. Laptop that connects to the engines and checks all the sensors.